In general, orthodontic treatment is performed in such a manner as to control an orthodontic appliance in a suitable position and direction, in order to move the entire teeth to be straight in a desired direction. For the movement, a plurality of brackets are installed on the teeth or band, and a wire for tooth correction is coupled to connect the plurality of brackets.
At this time, restoration force caused by the elasticity of the tooth correction wire is used to apply an orthodontic force, such as push, pull, or twist, to the teeth of a patient. Then, the teeth may be moved relative to one another.
As one treatment method of the above-described relative-movement orthodontic treatments, buccal-surface orthodontics may be used. However, when a patient wears such en orthodontic appliance, the orthodontic appliance may significantly influence the patient's daily life, thereby applying serious mental stress to the patient.
Furthermore, during such an orthodontic treatment, a tooth behind the canines may have to be extracted due to various reasons, and the entire front teeth including the canine may have to be towed to the rear. In order to move the front teeth to the rear while the arrangement of the front teeth are maintained as they originally were, a force must be applied to the center of resistance of the teeth.
The center of resistance refers to a point to which a force is applied to move a tooth planted in a hard bone, such that the tooth does not fall over. In general, the center of resistance of a front tooth is positioned between ⅓ and ½ of the distance from the ridge to the root of the tooth.
However, since an orthodontic appliance is attached on the teeth and a tooth correction wire is coupled to the orthodontic appliance, the point to which a force is applied is inevitably located at a lower position than the center of resistance at all times. In general, the center of resistance exists at a distance of about 10 mm above the position at which a bracket is attached. Thus, a force cannot be applied to the buccal surface from the center of resistance due to the structure of the oral cavity.
According to a recent orthodontic treatment, a tooth correction wire called a lever arm is installed on a lingual bracket, a soldering operation is performed to close a space, and a pulling force is applied from a position close to the center of resistance of a tooth to be corrected. When front teeth are towed to the rear during lingual correction, the lever arm is welded to the tooth correction wire for closing the space. Thus, the slope of the teeth may be adjusted according to an operator's intention.
In the above-described orthodontic treatment, however, since the soldering operation is performed, a lot of heat is required. When the heat is applied to the two tooth correction wires, the tooth correction wires may lose elasticity. Then, the tooth correction wires may not normally exhibit an orthodontic force when closing the space.
Hereafter, referring to FIG. 1, an orthodontic force measurement device for solving the above-described problem will be described. The orthodontic force measurement device has been disclosed in Korean Patent Laid-open Publication No. 10-2011-0067553.
The orthodontic force measurement device includes a support unit 10, a vernier caliper 20, an imaging device 30, a tooth correction wire 40, and a plurality of weights 50. The support unit 10 includes a base plate 11, a vernier caliper support part 12, a vernier caliper cover 13, a bracket 14, and an imaging device support part 15. The vernier caliper 20 is positioned at one side of the support unit 10. The imaging device 30 is positioned at the other side of the support unit 10. The tooth correction wire 40 is connected to the support unit 10. The plurality of weights 50 are positioned in the center of the tooth correction wire 40 and have different weights.
The orthodontic force measurement device uses measurement method based on an image obtained through the imaging device 30, which introduces measurement error. Thus, the orthodontic force measurement device cannot precisely measure an orthodontic force.
Furthermore, the orthodontic force measurement device can measure only an orthodontic force in a single direction through the weights 50. Thus, the orthodontic force measurement device cannot measure an orthodontic force in multiple directions.